Narrative:

I am writing this over my concern with the maintenance discrepancy we discovered on aircraft X; a hawker-siddeley hs-125-800XP in ZZZ may 2015. This airplane was flown in and then my partner and I were going to take passengers out roughly an hour later. When arriving to this airplane; the first thing I noticed was the sheer number of rusted screws on top of both the left and right wing of the airplane. Having been made aware of this problem affecting some of the hawkers; I felt that it needed to be evaluated and chose to write this up as well as some other discrepancies I found. During this time the other crewmember who brought the airplane in heard about my discrepancies and came out to discuss them. In talking about the rusted screws; he said something I found very interesting. He mentioned that he noticed them too and called maintenance control center (mcc) about them and was advised by the controller that it was really up to him and how he felt about them. As he has been in the hawker for quite some time and seen this; he didn't give them much thought and going by what mcc said; let it go.the next day we were assigned another airplane in ZZZ which gave me a chance to discuss aircraft X with the mechanic working it. It was in my discussion with this mechanic when I learned the outcome of my write-up. He showed me a document from the aircraft manufacturer that discussed the allowable corrosion. In it; it says; 'corrosion that is limited to only the head of the bolt (i.e. Fastener head and slot) is acceptable as long as there is no evidence of corrosion at the bolt/skin interface or on adjacent skin panel. Any indication of fastener damage beyond minor surface corrosion (i.e. Cracked; chipped or missing heads); or loose fasteners is unacceptable. Evidence of these conditions should be further assessed in accordance with (reference. 51-xx-xx) and repaired as necessary in accordance with (ref. 57-xx-xx; XXX).' well; just about every screw head on the top of the wings was rusted and exposed or breaking through the white paint. What the mechanics did was pick out some of the worse screws and using a paint scraper; broke the white paint away outside of the screw head exposing significant areas of corrosion on the skin. It was so bad on these screws and most likely all the others that the only effective way he said for it to be fixed was to get a ferry permit to send it to ZZZ1 as they have specialized equipment for this. He showed me some of the pictures of the corrosion that was sent to the aircraft manufacturer and I must say I was shocked how our company could allow an airplane to get this bad. I can't believe with all the [maintenance] checks that this was never looked at during inspection. From what I saw; this could not have been some recent occurrence but had been building for some time.also; in my talks with the mechanic; he mentioned something that surprised me. He mentioned that if the rust was only on the screw heads and found to be within tolerances; that a onetime inspection is all that is required. I found this hard to believe that some kind of additional inspection would not be required at a later time or the placement of a time interval until the corrosion had to be fixed. My concern is that a crewmember writes this up and the inspection shows the screw heads are within limits; how the next crew would handle it. They most likely will be told by mcc that the issue was previously dealt with and to be within tolerance. However; now due to the additional time; this screw head corrosion may now be out of tolerance. Also; with my dealings with mcc; I would be surprised if pushback from mcc wouldn't occur as they would try to tell you it had already been addressed. I guess what I am trying to say that when dealing with corrosion; I don't see how a onetime inspection of corrosion that is found to be within limits can be left as is. It could be quite some time later when finally addressed and the whole time the corrosion continues to get much worse.therefore; in the end I am providing this report in the hopes some concerns of mine can be answered. The first is how can our company [can] allow corrosion to manifest itself such as it did with this aircraft that the actions of a line pilot finally gets it addressed mandating a ferry permit when most likely it had been there for some time? Secondly; is it true that when corrosion is showing and found to be within limits that no other continuing inspection must be done? Finally; I am aware this condition has happened to 3-4 other aircraft and am wondering why this issue hasn't been addressed already? I can't imagine it being beneficial to the company to let this go and have a line pilot raise the issue causing the owner to be inconvenienced. Flight cancelled.

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Original NASA ASRS Text

Title: A Line Pilot questions how was it possible for one of their Hawker HS-125-800XP aircraft to have such a sheer number of rusted screws and fasteners on the upper surface of the left and right wing skin with all the Maintenance Checks performed on the aircraft. Corrosion had extended out from the wing skin screw heads; requiring a flight cancellation and Maintenance Ferry of the aircraft to Base for repairs.

Narrative: I am writing this over my concern with the maintenance discrepancy we discovered on Aircraft X; a Hawker-Siddeley HS-125-800XP in ZZZ May 2015. This airplane was flown in and then my partner and I were going to take passengers out roughly an hour later. When arriving to this airplane; the first thing I noticed was the sheer number of rusted screws on top of both the left and right wing of the airplane. Having been made aware of this problem affecting some of the Hawkers; I felt that it needed to be evaluated and chose to write this up as well as some other discrepancies I found. During this time the other crewmember who brought the airplane in heard about my discrepancies and came out to discuss them. In talking about the rusted screws; he said something I found very interesting. He mentioned that he noticed them too and called Maintenance Control Center (MCC) about them and was advised by the Controller that it was really up to him and how he felt about them. As he has been in the Hawker for quite some time and seen this; he didn't give them much thought and going by what MCC said; let it go.The next day we were assigned another airplane in ZZZ which gave me a chance to discuss Aircraft X with the Mechanic working it. It was in my discussion with this mechanic when I learned the outcome of my write-up. He showed me a document from the Aircraft Manufacturer that discussed the allowable corrosion. In it; it says; 'Corrosion that is limited to only the head of the bolt (i.e. fastener head and slot) is acceptable as long as there is no evidence of corrosion at the bolt/skin interface or on adjacent skin panel. Any indication of fastener damage beyond minor surface corrosion (i.e. cracked; chipped or missing heads); or loose fasteners is unacceptable. Evidence of these conditions should be further assessed in accordance with (REF. 51-XX-XX) and repaired as necessary in accordance with (Ref. 57-XX-XX; XXX).' Well; just about every screw head on the top of the wings was rusted and exposed or breaking through the white paint. What the mechanics did was pick out some of the worse screws and using a paint scraper; broke the white paint away outside of the screw head exposing significant areas of corrosion on the skin. It was so bad on these screws and most likely all the others that the only effective way he said for it to be fixed was to get a ferry permit to send it to ZZZ1 as they have specialized equipment for this. He showed me some of the pictures of the corrosion that was sent to the aircraft Manufacturer and I must say I was shocked how our company could allow an airplane to get this bad. I can't believe with all the [Maintenance] checks that this was never looked at during inspection. From what I saw; this could not have been some recent occurrence but had been building for some time.Also; in my talks with the Mechanic; he mentioned something that surprised me. He mentioned that if the rust was only on the screw heads and found to be within tolerances; that a onetime inspection is all that is required. I found this hard to believe that some kind of additional inspection would not be required at a later time or the placement of a time interval until the corrosion had to be fixed. My concern is that a crewmember writes this up and the inspection shows the screw heads are within limits; how the next crew would handle it. They most likely will be told by MCC that the issue was previously dealt with and to be within tolerance. However; now due to the additional time; this screw head corrosion may now be out of tolerance. Also; with my dealings with MCC; I would be surprised if pushback from MCC wouldn't occur as they would try to tell you it had already been addressed. I guess what I am trying to say that when dealing with corrosion; I don't see how a onetime inspection of corrosion that is found to be within limits can be left as is. It could be quite some time later when finally addressed and the whole time the corrosion continues to get much worse.Therefore; in the end I am providing this report in the hopes some concerns of mine can be answered. The first is how can our company [can] allow corrosion to manifest itself such as it did with this aircraft that the actions of a line pilot finally gets it addressed mandating a ferry permit when most likely it had been there for some time? Secondly; is it true that when corrosion is showing and found to be within limits that no other continuing inspection must be done? Finally; I am aware this condition has happened to 3-4 other aircraft and am wondering why this issue hasn't been addressed already? I can't imagine it being beneficial to the company to let this go and have a line pilot raise the issue causing the owner to be inconvenienced. Flight cancelled.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.